Yamuna's water is fully diverted to the Western Yamuna Canal up stream of Hathni Kund. Downstream of Wazirabad barrage, it is mostly sewage - treated, partially treated and untreated - emptied into the river by 18 drains.
"Yamuna is no longer an ecological entity. There is no oxygen…It is a dead (river), anaerobic. It releases ammonia and hydrogen sulphide among other toxic gases," explained Dr DD Basu, senior scientist from Central Pollution Control Board (CPCB).
But neither Delhi Pollution Control Committee nor any NGO has carried out any study to assess the damage being caused by the dangerous gases that hung over the river water. The CPCB has carried out certain investigations for measuring ammonia at a few places.
"(Now) we are carrying out an exhaustive study for ammonia. Later, we would do it for hydrogen sulphide," Basu said.